Monday, February 16, 2009

Anti-Smoking Advocates Reaffirm their Contention that All Who Don't Believe Secondhand Smoke Causes Lung Cancer are Comparable to Holocaust Deniers

In their reply to my response to their article in which they assert that scientists who have challenged the causal connection between secondhand smoke and lung cancer are comparable to Holocaust deniers, anti-smoking advocates Paschal Diethelm and Martin McKee reiterate this contention.

I had asserted that Diethelm and McKee's published article was arguing that anyone who fails to accept the conclusion that secondhand smoke causes lung cancer is a denialist on the order of those who deny that the Holocaust occurred. In their reply, Diethelm and McKee make no effort to soften or qualify their assertion or to suggest that I was over-interpreting their claim. Instead, they reiterate that they are indeed stating that those who don't accept that the small increased relative risk for lung cancer associated with secondhand smoke exposure reflects a causal relationship are denialists comparable to those who deny that the Holocaust happened.

They write: "We are not suggesting that those whom we define as denialists should be censored. Far from it. We simply propose that, as they established ground rules for debate that are not based on openness to evidence and scientific principles, we should recognise this and frame our arguments accordingly. Where there is genuine scientific controversy we, of course, believe in the need for informed and open debate using scientific evidence. However, this does not apply when one side uses highly selective evidence to suggest that there is genuine scientific uncertainty when this is not the case. Seemingly inadvertently, Professor Siegel makes our point. The 30% increase that he quotes is obtained from studies that compare the risk of disease in spouses of smokers and non-smokers, a weak study design (we will not rehearse the enormous effort by the tobacco industry to discredit even that research or its covert work to promote so-called “good epidemiological practice” that would dismiss relative risks of less than 2 as being unreliable). However, where direct measures of exposure are used (cotinine), the risk is substantially greater (relative hazard for coronary heart disease and stroke 1.57 (95% CI 1.08 to 2.28)). Yet this is only the beginning. As we have shown previously, the tobacco industry has long known (from its own secretly conducted animal experiments) that “room aged sidestream smoke” is much more toxic, volume for volume, than directly inhaled smoke, a finding that provides some explanation for the now common finding of rapid declines in coronary heart events following introduction of smoking bans."

Jacob Sullum nicely summarizes this discussion on Reason.com's Hit & Run blog. Sullum states: "Writing in the European Journal of Public Health, anti-smoking activists Pascal Diethelm and Martin McKee liken people who question the health hazards of secondhand smoke to people who do not believe HIV causes AIDS, people who think the world was created 6,000 years ago, people who are not persuaded that smoking causes cancer, people who maintain that climate change has "nothing to do with man-made CO2 emissions," and people who deny that the Holocaust happened. They say all are dishonest or deluded "denialists," trying to create controversy where there is no legitimate basis for it. Michael Siegel, an anti-smoking activist who agrees that prolonged exposure to secondhand smoke increases the risk of lung cancer and heart disease but questions some of the more extreme claims made by smoking ban advocates, likens Diethelm and McKee to religious fanatics. He has a point:

"Diethelm and McKee have endangered the integrity of public health by comparing those who challenge the conclusion that secondhand smoke causes heart disease and lung cancer with those who deny the Holocaust. As a primarily science-based movement, public health is supposed to have room for those who dissent from consensus opinions based on reasonable scientific grounds. To argue that those who fail to conclude that the small relative risk for lung cancer of 1.3 among persons exposed to secondhand smoke is indicative of a causal connection are comparable to Holocaust deniers is to turn public health into a religion, where the doctrines must be accepted on blind faith to avoid being branded as a heretic." ...

"In reply, Diethelm and McKee reject Siegel's analogy while hanging on to theirs, saying they are not advocating censorship of denialists. Of course, Siegel never said they were. Instead they are advocating branding, ad hominem attacks, and blithe dismissal."

The Rest of the Story

I was very surprised by Diethelm and McKee's reply. I was expecting them to soften the tone of their assertion or to qualify it in some way. I was also wondering whether they might back off somewhat from their contention that everyone who questions the causal link between secondhand smoke and lung cancer is the equivalent of a Holocaust denialist.

To my surprise, the authors not only reiterated their assertion that all those who question the link are denialists; they also strengthened their assertion by arguing that the use of selective data characterizes someone as a denialist who does not warrant a legitimate role in scientific discourse.

But most ironically, Diethelm and McKee themselves use selective data to argue that smoking bans result in an immediate reduction in heart attacks, which they say demonstrates that secondhand smoke causes heart disease. Specifically, they cite the "common finding" rapid declines in heart attacks following smoking bans as supporting their argument that the link between secondhand smoke and heart disease is undeniable.

Interestingly, if we used Diethelm and McKee's own criteria, we would have to conclude that they are denialists not worthy of scientific discourse because they selectively cite studies which have found rapid declines in heart attacks following smoking bans, yet they ignore both published and population-based data which fail to show any decline in acute cardiac events following smoking bans.

In fact, the one study that they do cite failed to find any significant effect of the smoking ban on heart attacks in Italy (see: Cesaroni G, Forastiere F, Agabiti N, et al. Effect of the Italian Smoking Ban on Population Rates of Acute Coronary Events. Circulation 2008). The data clearly show that the decline in heart attack rates among adults in the two age groups studied began prior to the implementation of the smoking ban. Thus, it is evident that the decline is not attributable to the smoking ban.

Take a look at the data for yourself:

A. Age 65-74

From 2003 to 2004 (prior to the smoking ban), the heart attack rate declined from 7.86 to 7.39, a drop of 6.0%.

From 2004 to 2005 (first year of the smoking ban), the heart attack rate declined from 7.39 to 6.95, a drop of 6.0%.

In other words, the decline in the heart attack rate from 2003 to 2004 was exactly the same as the decline from 2004 to 2005.

B. Age 35-64

From 2002 to 2003 (prior to the smoking ban), the heart attack rate declined from 2.13 to 1.95, a drop of 8.5%.

From 2004 to 2005 (the first year of the smoking ban), the heart attack rate declined from 1.92 to 1.80, a drop of 6.3%.

In other words, the observed decline in the heart attack rate one year prior to the smoking ban was actually greater than the decline in the heart attack rate after the smoking ban.

The average decline in the heart attack rate for the two year period preceding the smoking ban (2002 to 2004) was 4.9%.

The decline in the heart attack rate for the first year following the smoking ban was 6.4%.

Thus, one can see that the decline in the heart attack rate in this age group after the smoking ban was comparable to the decline in the heart attack rate in this age group before the smoking ban.

Once again, these data clearly do not support the conclusion that the smoking ban resulted in a sudden drop in the heart attack rate. If anything, these data document that the decline in the heart attack rate in this age group was about the same post-ban as it was pre-ban.

In light of these data, I find it impossible and highly invalid to conclude that the smoking ban resulted in the observed decline in heart attacks from 2004 to 2005. A more likely, and certainly plausible, explanation is that there was already a trend of declining heart attack rates and that this trend simply continued from 2004 to 2005.

What Diethelm and McKee are doing, then, is selectively citing data which they argue support their position, when in fact, those very data refute their position. In addition, they are leaving out data from published studies which demonstrate that the smoking ban in England had very little, if any, immediate effect on heart attacks as well as from population-based analyses (both in the U.S. and Scotland) which also demonstrate no significant effect of smoking bans on acute coronary events.

While I believe that Diethelm and McKee are not only wrong in their conclusion that smoking bans lead to rapid, dramatic reductions in heart attacks but also that the scientific basis for their conclusion is very shaky, I would never call them denialists for taking that position. It is simply an opinion. I disagree with their opinion and believe it is scientifically shoddy, but this doesn't make them denialists. At very worst, it just makes them wrong.

Or maybe I am wrong. But either way, it's not a question of one or the other of us being a denialist. It's simply a scientific debate.

Furthermore, I could also point out that even if it were true that smoking bans did lead to dramatic reductions in heart attacks, that would not necessarily demonstrate that secondhand smoke causes heart disease. The effects of these smoking bans could well be due to a decrease in active smoking, rather than to a decline in secondhand smoke exposure.

In summary, I strongly agree with Diethelm and McKee that secondhand smoke causes lung cancer and heart disease. I strongly disagree with Diethelm and McKee that smoking bans lead to dramatic, immediate reductions in heart attacks. Where does that leave us? It leaves us with a scientific debate. I respect their opinions in both cases, even though I happen to disagree with one of them. In no way are they denialists and despite what I feel is their selective use of particular data to support their position on smoking bans and heart attacks, I would never accuse them of being denialists. Their position, in fact, has nothing whatsoever to do with their character, which in my mind is simply not a part of the discussion.

For Diethelm and McKee, as for many in the modern-day anti-smoking movement, tobacco control is an ideology, rather than a science-based public health movement. If you disagree with the ideology, you are a denialist and have disqualified yourself from participating in the "scientific discourse." But the truth is that there is no longer any "scientific" discourse, because it is now an ideology where any studies reporting favorable findings are "good science" and any studies reporting unfavorable findings are automatically indicative of scientists of poor character.

As I have questioned the causal connection between smoking bans and immediate reductions in heart attacks, I am apparently of poor character.

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About Me

Dr. Siegel is a Professor in the Department of Community Health Sciences, Boston University School of Public Health. He has 32 years of experience in the field of tobacco control. He previously spent two years working at the Office on Smoking and Health at CDC, where he conducted research on secondhand smoke and cigarette advertising. He has published nearly 70 papers related to tobacco. He testified in the landmark Engle lawsuit against the tobacco companies, which resulted in an unprecedented $145 billion verdict against the industry. He teaches social and behavioral sciences, mass communication and public health, and public health advocacy in the Masters of Public Health program.